1. Technical Field
The present disclosure relates to an aptamer biosensor, and more particularly, to an aptamer sensor with improved sensitivity using a localized surface plasmon resonance (LSPR).
2. Description of the Related Art
The technology for rapidly measuring biomolecules has been recognized as an indispensable technology along with basic research on development of biosensors in medical field. Now that the relationship between the genome and the disease has become clearer by analysis of the human genome, a simple and easy-to-understand genetic diagnosis is required in the medical field, and development of relevant technology is ongoing. It is important to analyze interaction of biomolecules, but observing nanoscale biomolecules is not easy. Therefore, in recent years, researches on optical biosensors that combine biomolecules with plasmonic nanomaterials such as metal nanoparticles to observe phenomena occurring in a nano-sized space are increasingly being conducted. This is because the development of nanotechnology has made it possible to control plasmonic nanomaterials such as metal nanoparticles. Plasmonic nanomaterials are expected not only to be used as simple optical materials but also as tools for biosensor analysis.
In contrast with the case of bulk metal, when light having various wavelengths is emitted onto a material existing on a local surface such as metal nanoparticles, polarization occurs on the surface of metal nanoparticles and exhibits a unique characteristic of increasing the intensity of the electric field. Electrons formed by polarization form a group (plasmon) and locally vibrate on the surface of the metal nanoparticles. This phenomenon is called localized surface plasmon resonance (LSPR). This phenomenon has been theoretically calculated and predicted by Mie and others for a long time. Recently, as nanofabrication technology has been developed, useful researches on combination with various sensors have been published.
Similar to surface plasmon resonance (SPR), LSPR optical properties are sensitive to changes in dielectric constant, namely, refractive index, that occur near nanoparticles, allowing analysis of biomolecular interactions with relatively high sensitivity and ease. Therefore, by immobilizing various ligands on a single biochip based on LSPR optical properties as a detection principle, simultaneous analysis of multiple samples can be performed, compared to conventional biochips. Therefore, on-site monitoring required for unlabeled biochips is also possible.
The SPR phenomenon occurs in an electron-rich metal film. On the other hand, the LSPR phenomenon occurs on the surface of a nanometer-sized metal particle with a relatively limited amount of electrons, and accordingly vibration of electrons in the metal is weak, the size of the electric field caused by vibration of electrons is small. The small electromagnetic field reduces the range in which a material can be sensed, resulting in a reduced sensitivity to detect the target material. In particular, in measuring small molecular materials with low molecular weights, the limit of sensitivity is clear due to the small influence of the electromagnetic field. Therefore, there is a need for a technique for improving the sensitivity in measuring low molecular materials.
It should be understood that the foregoing description of the background art is merely for the purpose of promoting an understanding of the background of the present disclosure, and is not to be construed as admitting that the present disclosure corresponds to the prior art known to those skilled in the art.